Silicon photonics has significantly matured in the near-infrared (telecommunication) wavelength range with several
commercial products already in the market. More recently, the technology has been extended into the mid-infrared (mid-
IR) regime with potential applications in biochemical sensing, tissue photoablation, environmental monitoring and freespace
communications. The key advantage of silicon in the mid-IR, as compared with near-IR, is the absence of twophoton
absorption (TPA) and free-carrier absorption (FCA). The absence of these nonlinear losses would potentially
lead to high-performance nonlinear devices based on Raman and Kerr effects. Also, with the absence of TPA and FCA,
the coupled-wave equations that are usually numerically solved to model these nonlinear devices lend themselves to
analytical solutions in the mid-IR. In this paper, an analytical model for mid-IR silicon Raman lasers is developed. The
validity of the model is confirmed by comparing it with numerical solutions of the coupled-wave equations. The
developed model can be used as a versatile and efficient tool for analysis, design and optimization of mid-IR silicon
Raman lasers, or to find good initial guesses for numerical methods. The effects of cavity parameters, such as cavity
length and facet reflectivities, on the lasing threshold and input-output characteristics of the Raman laser are studied.
For instance, for a propagation loss of 0.5 dB/cm, conversion efficiencies as high as 56% is predicted. The predicted
optimum cavity (waveguide) length at 2.0 dB/cm propagation loss is ~ 3.4 mm. The results of this study predict strong
prospects for mid-IR silicon Raman lasers for the mentioned applications.